1 解 :原式 = 1.2 ×2.5
=0.3×(4×2.5)
=0.3×10
= 3
2 原式 = 6.74×1.8-1.8×1.74
=1.8 × ( 6.74 - 1.74)
= 1.8 × 5
= 9
3 解 :原式 = （6分之1＋4分之1-8分之1）×480
=1/6 ×480 + 1/4 × 480 - 1/8 × 480
= 80 + 120 - 60
= 140
4 解 :原式 = 3.54×99＋3.54
= 3.54 × ( 99 + 1 )
= 3.54 × 100
= 354
5 解 :原式 = 272÷125
=272 ÷5÷ 5
= 54.4 ÷ 5÷ 5
=2.176
6 解 :原式 = 0.38×3.5＋0.038×65
= 0.038 × ( 3.5× 10 + 65)
= 0.038 × 100
= 3.8
7 原式 = 21＋22＋23＋24＋.100
= 10 × ( 20 + 30 + 40 + 50 + 60 + 70 + 80 + 90) + 8× (1 + 2 + .9) + 100
= 10× 440 + 8 × 45 + 100
= 4400 + 360 + 100
= 44860